A session-based common-tier encryption (SBCTE) delivery of video on demand (VOD) may rely on a mixture of regular session-based encryption (SBE) as well as common-tier encryption (CTE). When VOD content is delivered using CTE in an environment with multiple types of set-top boxes (STBs) each using a different conditional access system (CAS), a simulcrypt encryptor can be used to encrypt the video and insert multiple entitlement control messages (ECMs) into that video. These ECMs are for all the CAS types required to support the STBs that the video stream is delivered to. This may result in extra load on the ECM generators because the targeted STB will have a particular CAS and thus only use one of the multiple ECMs.
For example, a simulcrypt video encryption system, when deployed, will use a common-tier encryption to deliver VOD to customers. This means that all VOD sessions, will be carrying ECMs for multiple CASs, so that the ECM generators will be generating many ECMs that are never used.